floatdidf.c revision 1.5
11.5Sscw/* $NetBSD: floatdidf.c,v 1.5 2002/10/20 10:15:47 scw Exp $ */ 21.3Scgd 31.1Smycroft/*- 41.1Smycroft * Copyright (c) 1992, 1993 51.1Smycroft * The Regents of the University of California. All rights reserved. 61.1Smycroft * 71.1Smycroft * This software was developed by the Computer Systems Engineering group 81.1Smycroft * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 91.1Smycroft * contributed to Berkeley. 101.1Smycroft * 111.1Smycroft * Redistribution and use in source and binary forms, with or without 121.1Smycroft * modification, are permitted provided that the following conditions 131.1Smycroft * are met: 141.1Smycroft * 1. Redistributions of source code must retain the above copyright 151.1Smycroft * notice, this list of conditions and the following disclaimer. 161.1Smycroft * 2. Redistributions in binary form must reproduce the above copyright 171.1Smycroft * notice, this list of conditions and the following disclaimer in the 181.1Smycroft * documentation and/or other materials provided with the distribution. 191.1Smycroft * 3. All advertising materials mentioning features or use of this software 201.1Smycroft * must display the following acknowledgement: 211.1Smycroft * This product includes software developed by the University of 221.1Smycroft * California, Berkeley and its contributors. 231.1Smycroft * 4. Neither the name of the University nor the names of its contributors 241.1Smycroft * may be used to endorse or promote products derived from this software 251.1Smycroft * without specific prior written permission. 261.1Smycroft * 271.1Smycroft * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 281.1Smycroft * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 291.1Smycroft * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 301.1Smycroft * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 311.1Smycroft * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 321.1Smycroft * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 331.1Smycroft * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 341.1Smycroft * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 351.1Smycroft * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 361.1Smycroft * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 371.1Smycroft * SUCH DAMAGE. 381.1Smycroft */ 391.1Smycroft 401.4Schristos#include <sys/cdefs.h> 411.1Smycroft#if defined(LIBC_SCCS) && !defined(lint) 421.3Scgd#if 0 431.3Scgdstatic char sccsid[] = "@(#)floatdidf.c 8.1 (Berkeley) 6/4/93"; 441.3Scgd#else 451.5Sscw__RCSID("$NetBSD: floatdidf.c,v 1.5 2002/10/20 10:15:47 scw Exp $"); 461.3Scgd#endif 471.1Smycroft#endif /* LIBC_SCCS and not lint */ 481.1Smycroft 491.1Smycroft#include "quad.h" 501.1Smycroft 511.1Smycroft/* 521.1Smycroft * Convert (signed) quad to double. 531.1Smycroft */ 541.1Smycroftdouble 551.1Smycroft__floatdidf(x) 561.1Smycroft quad_t x; 571.1Smycroft{ 581.1Smycroft double d; 591.1Smycroft union uu u; 601.1Smycroft int neg; 611.1Smycroft 621.1Smycroft /* 631.1Smycroft * Get an unsigned number first, by negating if necessary. 641.1Smycroft */ 651.1Smycroft if (x < 0) 661.1Smycroft u.q = -x, neg = 1; 671.1Smycroft else 681.1Smycroft u.q = x, neg = 0; 691.1Smycroft 701.1Smycroft /* 711.1Smycroft * Now u.ul[H] has the factor of 2^32 (or whatever) and u.ul[L] 721.5Sscw * has the units. Ideally we could just set d, add INT_BITS to 731.1Smycroft * its exponent, and then add the units, but this is portable 741.1Smycroft * code and does not know how to get at an exponent. Machine- 751.1Smycroft * specific code may be able to do this more efficiently. 761.1Smycroft */ 771.5Sscw d = (double)u.ul[H] * (((int)1 << (INT_BITS - 2)) * 4.0); 781.1Smycroft d += u.ul[L]; 791.1Smycroft 801.1Smycroft return (neg ? -d : d); 811.1Smycroft} 82